Golf balls having a low modulus HNP layer and a high modulus HNP layer

ABSTRACT

The present invention is directed to golf balls consisting of a dual-layer core and a cover. The core consists of an inner core layer formed from a high modulus HNP composition and an outer core layer formed from a low modulus HNP composition. The outer core layer has an outer surface hardness less than the outer surface hardness of the inner core layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/694,007, filed Mar. 30, 2007 now U.S. Pat. No. 7,452,290.This application is also a continuation-in-part of U.S. patentapplication Ser. No. 11/972,227, filed Jan. 10, 2008 now abandoned. Theentire disclosure of each of these references is hereby incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention is directed to golf balls comprising a core and acover, wherein the core consists of a layer formed from a low modulusHNP composition and a layer formed from a high modulus HNP composition.The present invention is not limited by which core layer is formed fromthe low modulus HNP composition and which core layer is formed from thehigh modulus HNP composition, so long as both layers are present in thecore of the golf ball.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., singlelayer core and single layer cover), and multi-layer (i.e., solid core ofone or more layers and/or a cover of one or more layers) golf balls.Wound golf balls typically include a solid, hollow, or fluid-filledcenter, surrounded by a tensioned elastomeric material, and a cover.

Golf ball core and cover layers are typically constructed with polymercompositions including, for example, polybutadiene rubber,polyurethanes, polyamides, ionomers, and blends thereof. Ionomers,particularly ethylene-based ionomers, are a preferred group of polymersfor golf ball layers because of their toughness, durability, and widerange of hardness values.

Golf ball compositions comprising highly neutralized acid polymers areknown. For example, U.S. Patent Application Publication No.2003/0130434, the entire disclosure of which is hereby incorporatedherein by reference, discloses melt-processible, highly-neutralizedethylene acid copolymers and process for making them by incorporating analiphatic, mono-functional organic acid in the acid copolymer and thenneutralizing greater than 90% of all the acid groups present. The use ofsuch compositions in various golf ball layers is disclosed. Also, U.S.Patent Application Publication No. 2005/0148725, the entire disclosureof which is hereby incorporated herein by reference, discloses ahighly-resilient thermoplastic composition comprising (a) an acidcopolymer, (b) a salt of a high molecular weight, monomeric organicacid; (c) a thermoplastic resin; (d) a cation source; and (e)optionally, a filler. The reference also discloses one-piece, two-piece,three-piece, and multi-layered golf balls comprising thehighly-resilient thermoplastic composition.

While various uses for highly neutralized acid polymers in golf ballshave been discovered, there is a need in the industry to broaden theapplicability of highly neutralized acid polymers to particular golfball constructions having desirable spin, feel, and COR properties. Thepresent invention provides such golf ball constructions through the useof a layer formed from a low modulus HNP composition and a layer formedfrom a high modulus HNP composition.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a golf ballconsisting of a core and a cover, wherein the core has an overalldiameter of from 1.400 inches to 1.660 inches and consists of an innercore layer and an outer core layer. The inner core layer has a diameterof from 0. 125 inches to 0.750 inches, an outer surface hardness of 70Shore C or greater, and is formed from a high modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid copolymerhaving a modulus of from 25,000 psi to 150,000 psi. The outer core layerhas an outer surface hardness less than the outer surface hardness ofthe inner core layer and is formed from a low modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid/alkyl(meth)acrylate copolymer having a modulus of from 1,000 psi to 50,000psi. The modulus of the highly neutralized copolymer of the low modulusHNP composition is at least 10% less than the modulus of the highlyneutralized copolymer of the high modulus HNP composition.

In another embodiment, the present invention is directed to a golf ballconsisting of a core and a cover. The core has an overall diameter offrom 1.400 inches to 1.620 inches and consists of an inner core layerand an outer core layer. The inner core layer has a diameter of from0.250 inches to 0.500 inches, an outer surface hardness of 81 Shore C orgreater, and is formed from a high modulus HNP composition comprising ahighly neutralized ethylene/(meth)acrylic acid copolymer having amodulus of from 25,000 psi to 150,000 psi. The outer core layer has anouter surface hardness of 90 Shore C or less and is formed from a lowmodulus HNP composition comprising a highly neutralizedethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer having amodulus of from 1,000 psi to 50,000 psi. The modulus of the highlyneutralized copolymer of the low modulus HNP composition is at least 10%less than the modulus of the highly neutralized copolymer of the highmodulus HNP composition. The cover consists of inner cover layer and anouter cover layer. The inner cover layer has an outer surface hardnessof 65 Shore D or greater and a thickness of from 0.020 inches to 0.080inches. The outer cover layer has a surface hardness of 60 Shore D orless and a thickness of from 0.015 inches to 0.055 inches.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a golf ball according to anembodiment of the present invention.

FIG. 2 is a cross-sectional view of a golf ball according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a golf ball 20 according to an embodiment of the presentinvention, including an inner core layer 22, an outer core layer 24, anda cover 26. While shown in FIG. 1 as a single layer, cover 26 may be asingle-, dual-, or multi-layer cover. FIG. 2 shows a golf ball 30according to an embodiment of the present invention, including an innercore layer 32, an outer core layer 34, an inner cover layer 36, and anouter cover layer 38.

Golf balls of the present invention have at least two layers formed fromhighly neutralized acid polymer (“HNP”) compositions. More particularly,golf balls of the present invention have at least one layer formed froma low modulus HNP composition, and at least one layer formed from a highmodulus HNP composition.

As used herein, “highly neutralized acid polymer” refers to an acidpolymer after at least 80%, preferably at least 90%, more preferably atleast 95%, and even more preferably 100%, of the acid groups of the acidpolymer are neutralized.

Low Modulus HNP Composition

Low modulus HNP compositions of the present invention comprise at leastone low modulus HNP having a modulus within a range having a lower limitof 1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 25,000or 28,000 or 30,000 or 35,000 or 45,000 or 50,000 or 55,000 psi. In apreferred embodiment, the modulus of the low modulus HNP is at least 10%less, or at least 20% less, or at least 25% less, or at least 30% less,or at least 35% less, than the modulus of the high modulus HNP.

Low modulus HNPs of the present invention are salts of acid copolymers.It is understood that the low modulus HNP may be a blend of two or morelow modulus HNPs. The acid copolymer of the low modulus HNP is anO/X/Y-type copolymer, wherein O is an α-olefin, X is a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningmonomer. O is preferably ethylene. X is preferably selected from (meth)acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric acid,and itaconic acid. (Meth) acrylic acid is particularly preferred. Asused herein, “(meth) acrylic acid” means methacrylic acid and/or acrylicacid. Likewise, “(meth) acrylate” means methacrylate and/or acrylate. Yis preferably an alkyl (meth) acrylate, wherein the alkyl groups havefrom 1 to 8 carbon atoms. Preferred O/X/Y-type copolymers are thosewherein O is ethylene, X is (meth) acrylic acid, and Y is selected from(meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,methyl (meth) acrylate, and ethyl (meth) acrylate. Particularlypreferred O/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butylacrylate, ethylene/(meth) acrylic acid/methyl acrylate, andethylene/(meth) acrylic acid/ethyl acrylate.

The acid copolymer of the low modulus HNP typically includes theα-olefin in an amount of at least 15 wt %, or at least 25 wt %, or atleast 40 wt %, or at least 60 wt %, based on the total weight of theacid copolymer. The amount of C₃-C₈ α,β-ethylenically unsaturatedcarboxylic acid in the acid copolymer is typically within a range havinga lower limit of 1 or 4 or 6 or 8 or 10 or 15 wt % and an upper limit of20 or 35 or 40 wt %, based on the total weight of the acid copolymer.The amount of softening monomer in the acid copolymer is typicallywithin a range having a lower limit of 1 or 3 or 5 or 11 or 15 or 20 wt% and an upper limit of 23 or 25 or 30 or 35 or 50 wt %, based on thetotal weight of the acid copolymer.

Particularly suitable acid copolymers of the low modulus HNP includevery low modulus ionomer- (“VLMI-”) type ethylene-acid polymers, such asSurlyn® 6320, Surlyn® 8120, Surlyn® 8320, and Surlyn® 9320. Surlyn®ionomers are commercially available from E. I. du Pont de Nemours andCompany. Also suitable are DuPont® HPF 1000 and DuPont® HPF 2000,ionomeric materials commercially available from E. I. du Pont de Nemoursand Company.

Additional suitable acid copolymers of the low modulus HNP aredisclosed, for example, in U.S. Patent Application Publication Nos.2005/0148725, 2005/0020741, 2004/0220343, and 2003/0130434, and U.S.Pat. Nos. 5,691,418, 6,562,906, 6,653,382, 6,777,472, 6,762,246, and6,815,480, the entire disclosures of which are hereby incorporatedherein by reference.

In a preferred embodiment, the low modulus HNP is formed by reacting anacid copolymer, which is optionally partially neutralized, with asufficient amount of cation source, in the presence of a high molecularweight organic acid or salt thereof, such that at least 80%, preferablyat least 90%, more preferably at least 95%, and even more preferably100%, of all acid groups present are neutralized. The acid copolymer canbe reacted with the high molecular weight organic acid or salt thereofand the cation source simultaneously, or the acid copolymer can bereacted with the high molecular weight organic acid prior to theaddition of the cation source.

Suitable high molecular weight organic acids are aliphatic organicacids, aromatic organic acids, saturated monofunctional organic acids,unsaturated monofunctional organic acids, multi-unsaturatedmonofunctional organic acids, and dimerized derivatives thereof.Particular examples of suitable organic acids include, but are notlimited to, caproic acid, caprylic acid, capric acid, lauric acid,stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid,myristic acid, benzoic acid, palmitic acid, phenylacetic acid,naphthalenoic acid, dimerized derivatives thereof, and combinationsthereof Salts of high molecular weight organic acids comprise the salts,particularly the barium, lithium, sodium, zinc, bismuth, chromium,cobalt, copper, potassium, stontium, titanium, tungsten, magnesium, andcalcium salts, of aliphatic organic acids, aromatic organic acids,saturated monofunctional organic acids, unsaturated monofunctionalorganic acids, multi-unsaturated monofunctional organic acids, dimerizedderivatives thereof, and combinations thereof Suitable organic acids andsalts thereof are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals. The acid copolymer may be at leastpartially neutralized prior to contacting the acid copolymer with thecation source to form the low modulus HNP. Methods of preparing ionomersare well known, and are disclosed, for example, in U.S. Pat. No.3,264,272, the entire disclosure of which is hereby incorporated hereinby reference. The acid copolymer can be a direct copolymer wherein thepolymer is polymerized by adding all monomers simultaneously, asdisclosed, for example, in U.S. Pat. No. 4,351,931, the entiredisclosure of which is hereby incorporated herein by reference.Alternatively, the acid copolymer can be a graft copolymer wherein amonomer is grafted onto an existing polymer, as disclosed, for example,in U.S. Patent Application Publication No. 2002/0013413, the entiredisclosure of which is hereby incorporated herein by reference.

Low modulus HNP compositions of the present invention optionally containone or more melt flow modifiers. The amount of melt flow modifier in thecomposition is readily determined such that the melt flow index of thecomposition is at least 0.1 g/10 min, preferably from 0.5 g/10 min to10.0 g/10 min, and more preferably from 1.0 g/10 min to 6.0 g/10 min, asmeasured using ASTM D-1238, condition E, at 190° C., using a 2160 gramweight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

Low modulus HNP compositions of the present invention optionally includeadditive(s) and/or filler(s) in an amount of 50 wt % or less, or 30 wt %or less, or 15 wt % or less, based on the total weight of the lowmodulus HNP composition. Suitable additives and fillers include, but arenot limited to, chemical blowing and foaming agents, opticalbrighteners, coloring agents, fluorescent agents, whitening agents, UVabsorbers, light stabilizers, defoaming agents, processing aids, mica,talc, nano-fillers, antioxidants, stabilizers, softening agents,fragrance components, plasticizers, impact modifiers, TiO₂, acidcopolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide,barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinccarbonate, barium carbonate, clay, tungsten, tungsten carbide, silica,lead silicate, regrind (recycled material), and mixtures thereofSuitable additives are more fully described in, for example, U.S. PatentApplication Publication No. 2003/0225197, the entire disclosure of whichis hereby incorporated herein by reference.

Low modulus HNP compositions of the present invention optionally containa high modulus HNP.

Low modulus HNP compositions of the present invention preferably have amaterial hardness within a range having a lower limit of 40 or 50 or 55Shore C and an upper limit of 70 or 80 or 87 Shore C.

In a particular embodiment, the low modulus HNP composition has amoisture vapor transmission rate of 8 g-mil/100 in²/day or less (i.e.,3.2 g-mm/m²·day or less), or 5 g-mil/100 in²/day or less (i.e., 2.0g-mm/m²·day or less), or 3 g-mil/100 in²/day or less (i.e., 1.2 g-mm/m²·day or less), or 2 g-mil/100 in²/day or less (i.e., 0.8 g-mm/m²·dayor less), or 1 g-mil/100 in²/day or less (i.e., 0.4 g-mm/m²·day orless), or less than 1 g-mil/100 in²/day (i.e., less than 0.4g-mm/m²·day). As used herein, moisture vapor transmission rate (“MVTR”)is given in g-mil/100 in²/day, and is measured at 20° C. and accordingto ASTM F1249-99. In a preferred aspect of this embodiment, the lowmodulus HNP composition comprises a low modulus HNP prepared using acation source which is less hydrophilic than conventionalmagnesium-based cation sources. Suitable moisture resistant HNPcompositions are disclosed, for example, in U.S. Patent ApplicationPublication Nos. 2005/0267240, 2006/0106175 and 2006/0293464, the entiredisclosures of which are hereby incorporated herein by reference.

In another particular embodiment, a sphere formed from the low modulusHNP composition has a compression of 80 or less, or 70 or less, or 65 orless, or 60 or less, or 50 or less, or 40 or less, or 30 or less, or 20or less.

Low modulus HNP compositions of the present invention are not limited byany particular method or any particular equipment for making thecompositions. In a preferred embodiment, the composition is prepared bythe following process. The acid polymer(s), preferably a VLMI-typeethylene-acid terpolymer, high molecular weight organic acid(s) orsalt(s) thereof, and optionally additive(s)/filler(s) are simultaneouslyor individually fed into a melt extruder, such as a single or twin screwextruder. A suitable amount of cation source is simultaneously orsubsequently added such that at least 80%, preferably at least 90%, morepreferably at least 95%, and even more preferably 100%, of all acidgroups present are neutralized. The acid polymer may be at leastpartially neutralized prior to the above process. The components areintensively mixed prior to being extruded as a strand from the die-head.

Low modulus HNP compositions of the present invention may be blendedwith one or more additional polymers, such as thermoplastic polymers andelastomers. Examples of thermoplastic polymers suitable for blendinginclude, but are not limited to, bimodal ionomers (e.g., as disclosed inU.S. Patent Application Publication No. 2004/0220343 and U.S. Pat. Nos.6,562,906, 6,762,246 and 7,273,903, the entire disclosures of which arehereby incorporated herein by reference), ionomers modified with rosins(e.g., as disclosed in U.S. Patent Application Publication No.2005/0020741, the entire disclosure of which is hereby incorporated byreference), soft and resilient ethylene copolymers (e.g., as disclosedU.S. Patent Application Publication No. 2003/0114565, the entiredisclosure of which is hereby incorporated herein by reference)polyolefins, polyamides, polyesters, polyethers, polycarbonates,polysulfones, polyacetals, polylactones, acrylonitrile-butadiene-styreneresins, polyphenylene oxide, polyphenylene sulfide,styrene-acrylonitrile resins, styrene maleic anhydride, polyimides,aromatic polyketones, ionomers and ionomeric precursors, acidcopolymers, conventional HNPs, polyurethanes, grafted and non-graftedmetallocene-catalyzed polymers, single-site catalyst polymerizedpolymers, high crystalline acid polymers, cationic ionomers, andcombinations thereof. Particular polyolefins suitable for blendinginclude one or more, linear, branched, or cyclic, C₂-C₄₀ olefins,particularly polymers comprising ethylene or propylene copolymerizedwith one or more C₂-C₄₀ olefins, C₃-C₂₀ α-olefins, or C₃-C₁₀ α-olefins.Particular conventional HNPs suitable for blending include, but are notlimited to, one or more of the HNPs disclosed in U.S. Pat. Nos.6,756,436, 6,894,098, and 6,953,820, the entire disclosures of which arehereby incorporated herein by reference. Examples of elastomers suitablefor blending with the invention polymers include natural and syntheticrubbers, including, but not limited to, ethylene propylene rubber(“EPR”), ethylene propylene diene rubber (“EPDM”), styrenic blockcopolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where“S” is styrene, “I” is isobutylene, and “B” is butadiene), butyl rubber,halobutyl rubber, copolymers of isobutylene and para-alkylstyrene,halogenated copolymers of isobutylene and para-alkylstyrene, naturalrubber, polyisoprene, copolymers of butadiene with acrylonitrile,polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber,acrylonitrile chlorinated isoprene rubber, and polybutadiene rubber (cisand trans). Additional suitable blend polymers include those describedin U.S. Pat. No. 5,981,658, for example at column 14, lines 30 to 56,the entire disclosure of which is hereby incorporated herein byreference. The blends described herein may be produced by post-reactorblending, by connecting reactors in series to make reactor blends, or byusing more than one catalyst in the same reactor to produce multiplespecies of polymer. The polymers may be mixed prior to being put into anextruder, or they may be mixed in an extruder.

Particularly suitable low modulus HNP compositions include, but are notlimited to, the highly-resilient thermoplastic compositions disclosed inU.S. Patent Application Publication No. 2005/0148725; thehighly-neutralized ethylene copolymers disclosed in U.S. Pat. Nos.6,653,382 and 6,777,472, and U.S. Patent Application Publication No.2003/0130434; and the highly-resilient thermoplastic elastomercompositions disclosed in U.S. Pat. No. 6,815,480; the entiredisclosures of which are hereby incorporated herein by reference.

High Modulus HNP Composition

High modulus HNP compositions of the present invention comprise at leastone high modulus HNP having a modulus within a range having a lowerlimit of 25,000 or 27,000 or 30,000 or 40,000 or 45,000 or 50,000 or55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or 100,000or 150,000 psi.

High modulus HNPs of the present invention are salts of acid copolymers.It is understood that the high modulus HNP may be a blend of two or morehigh modulus HNPs. Preferred acid copolymers are copolymers of anα-olefin and a C₃-C₈ α,β-ethylenically unsaturated carboxylic acid. Theacid is typically present in the acid copolymer in an amount within arange having a lower limit of 1 or 10 or 12 or 15 or 20 wt % and anupper limit of 25 or 30 or 35 or 40 wt %, based on the total weight ofthe acid copolymer. The α-olefin is preferably selected from ethyleneand propylene. The acid is preferably selected from (meth) acrylic acid,ethacrylic acid, maleic acid, crotonic acid, fumaric acid, and itaconicacid. (Meth) acrylic acid is particularly preferred. In a preferredembodiment, the high modulus HNP has a higher level of acid than the lowmodulus HNP.

Suitable acid copolymers include partially neutralized acid polymers.Examples of suitable partially neutralized acid polymers include, butare not limited to, Surlyn® ionomers, commercially available from E. I.du Pont de Nemours and Company; AClyn® ionomers, commercially availablefrom Honeywell International Inc.; and Iotek® ionomers, commerciallyavailable from ExxonMobil Chemical Company. Also suitable are DuPont®HPF 1000 and DuPont® HPF 2000, ionomeric materials commerciallyavailable from E. I. du Pont de Nemours and Company. Additional suitableacid polymers are more fully described, for example, in U.S. Pat. Nos.6,562,906, 6,762,246, and 6,953,820 and U.S. Patent ApplicationPublication Nos. 2005/0049367, 2005/0020741, and 2004/0220343, theentire disclosures of which are hereby incorporated herein by reference.

In a preferred embodiment, the high modulus HNP is formed by reacting anacid copolymer with a sufficient amount of cation source such that atleast 80%, preferably at least 90%, more preferably at least 95%, andeven more preferably 100%, of all acid groups present are neutralized.Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof. Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals. Metal ions and compounds of calcium andmagnesium are particularly preferred. The acid copolymer may be at leastpartially neutralized prior to contacting the acid copolymer with thecation source to form the high modulus HNP. As previously stated,methods of preparing ionomers, and the acid copolymers on which ionomersare based, are disclosed, for example, in U.S. Pat. Nos. 3,264,272, and4,351,931, and U.S. Patent Application Publication No. 2002/0013413.

High modulus HNP compositions of the present invention optionallycontain one or more melt flow modifiers. The amount of melt flowmodifier in the composition is readily determined such that the meltflow index of the composition is at least 0.1 g/10 min, preferably from0.5 g/10 min to 10.0 g/10 min, and more preferably from 1.0 g/10 min to6.0 g/10 min, as measured using ASTM D-1238, condition E, at 190° C.,using a 2160 gram weight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

High modulus HNP compositions of the present invention optionallyinclude additive(s) and/or filler(s) in an amount within a range havinga lower limit of 0 or 5 or 10 wt %, and an upper limit of 25 or 30 or 50wt %, based on the total weight of the high modulus HNP composition.Suitable additives and fillers include those previously described assuitable for the low modulus HNP compositions of the present invention.

In addition to the high modulus HNP, optional melt flow modifier(s), andoptional additive(s) and/or filler(s), the high modulus HNP compositionof the present invention may contain a low modulus HNP.

In a particular embodiment, the high modulus HNP composition has an MVTRof 8 g-mil/100 in²/day or less (i.e., 3.2 g-mm/m²·day or less), or 5g-mil/100 in²/day or less (i.e., 2.0 g-mm/m²·day or less), or 3g-mil/100 in²/day or less (i.e., 1.2 g-mm/m²·day or less), or 2g-mil/100 in²/day or less (i.e., 0.8 g-mm/m²·day or less), or 1g-mil/100 in²/day or less (i.e., 0.4 g-mm/m²·day or less), or less than1 g-mil/100 in²/day (i.e., less than 0.4 g-mm/m²·day). In a preferredaspect of this embodiment, the high modulus HNP composition comprises ahigh modulus HNP prepared using a cation source which is lesshydrophilic than conventional magnesium-based cation sources. Suitablemoisture resistant HNP compositions are disclosed, for example, incopending U.S. patent application Ser. No. 11/270,066 and U.S. PatentApplication Publication No. 2005/0267240, the entire disclosures ofwhich are hereby incorporated herein by reference.

In another particular embodiment, a sphere formed from the high modulusHNP composition has a compression of 70 or greater, or 80 or greater, ora compression within a range having a lower limit of 70 or 80 or 90 or100 and an upper limit of 110 or 130 or 140.

High modulus HNP compositions of the present invention are not limitedby any particular method or any particular equipment for making thecompositions. In a preferred embodiment, the composition is prepared bythe following process. The acid polymer(s), preferably anethylene/(meth) acrylic acid copolymer, optional melt flow modifier(s),and optional additive(s)/filler(s) are simultaneously or individuallyfed into a melt extruder, such as a single or twin screw extruder. Asuitable amount of cation source is then added such that at least 80%,preferably at least 90%, more preferably at least 95%, and even morepreferably 100%, of all acid groups present are neutralized. The acidpolymer may be at least partially neutralized prior to the aboveprocess. The components are intensively mixed prior to being extruded asa strand from the die-head.

In another preferred embodiment, the high modulus HNP composition isformed by combining a low modulus HNP with a sufficient amount of one ormore additional material(s), including, but not limited to, additives,fillers, and polymeric materials, to increase the modulus such that theresulting composition has a modulus as described above for the highmodulus HNP.

HNP compositions of the present invention may be blended with one ormore additional polymers, such as thermoplastic polymers and elastomers.Examples of thermoplastic polymers and elastomers suitable for blendinginclude those previously described as suitable for blending with the lowmodulus HNP compositions of the present invention.

HNP compositions of the present invention, in the neat (i.e., unfilled)form, preferably have a specific gravity of from 0.95 g/cc to 0.99 g/cc.Any suitable filler, flake, fiber, particle, or the like, of an organicor inorganic material may be added to the HNP composition to increase ordecrease the specific gravity, particularly to adjust the weightdistribution within the golf ball, as further disclosed in U.S. Pat.Nos. 6,494,795, 6,547,677, 6,743,123, 7,074,137, and 6,688,991, theentire disclosures of which are hereby incorporated herein by reference.

Golf Ball Applications

Golf balls of the present invention comprise at least one layer formedfrom a low modulus HNP composition and at least one layer formed from ahigh modulus HNP composition. In a preferred embodiment, the presentinvention provides a golf ball having a two-layer core, wherein thetwo-layer core includes a layer formed from a low modulus HNPcomposition and a layer formed from a high modulus HNP composition.

In the embodiments disclosed herein, the low modulus HNP compositionand/or the high modulus HNP composition can be either foamed or filledwith density adjusting materials to provide desirable golf ballperformance characteristics.

Golf balls having a layer formed from a low modulus HNP composition anda layer formed from a high modulus HNP composition are furtherdisclosed, for example, in U.S. Pat. No. 7,211,008, the entiredisclosure of which is hereby incorporated herein by reference.

Two-layer cores of the present invention consist of an inner core layerand an outer core layer, and preferably have an overall core diameterwithin a range having a lower limit of 1.400 or 1.450 or 1.500 or 1.5 10or 1.550 inches and an upper limit of 1.600 or 1.620 or 1.660 inches.The inner core layer preferably has a diameter within a range having alower limit of 0.100 or 0.125 or 0.250 inches and an upper limit of0.375 or 0.500 or 0.750 or 1.000 inches.

The inner core layer preferably has an outer surface hardness of 70Shore C or greater, or 81 Shore C or greater, or 85 Shore C or greater,or an outer surface hardness within a range having a lower limit of 70or 80 Shore C and an upper limit of 90 or 95 Shore C. The outer corelayer preferably has an outer surface hardness of 90 Shore C or less, or80 Shore C or less, or less than 80 Shore C, or less than 70 Shore C, orless than 60 Shore C. In a particular embodiment, the Shore C hardnessof the outer core layer's outer surface is less than or equal to that ofthe inner core layer's outer surface. In another particular embodiment,the Shore C hardness of the outer core layer's outer surface is lessthan that of the inner core layer's outer surface.

The specific gravity of the outer core layer is preferably greater thanor equal to or substantially the same as the specific gravity of theinner core layer. For purposes of the present invention, specificgravities are substantially the same if they are the same or within 0.1g/cc of each other.

While the present invention is not limited by which core layer is formedfrom the low modulus HNP composition and which core layer is formed fromthe high modulus HNP composition, the inner core layer is preferablyformed from the high modulus HNP composition and the outer core layer ispreferably formed from the low modulus HNP composition.

Golf ball cores of the present invention are not limited by anyparticular hardness for the center point of the inner core layer. In aparticular embodiment, the center hardness is within a range having alower limit of 30 or 40 or 45 Shore C and an upper limit of 70 or 75 or80 Shore C. In another embodiment, the center hardness is within a rangehaving a lower limit of 60 or 65 Shore C and an upper limit of 80 or 85or 90 or 95 Shore C.

The two-layer core is enclosed by a cover, which may be a single-,dual-, or multi-layer cover, preferably having an overall thicknesswithin a range having a lower limit of 0.010 or 0.015 or 0.020 or 0.025or 0.030 or 0.040 or 0.045 or 0.050 or 0.055 or 0.060 inches and anupper limit of 0.070 or 0.075 or 0.080 or 0.090 or 0.100 or 0.110 or0.120 or 0.140 or 0.150 or 0.200 or 0.300 or 0.500 inches. Dual- andmulti-layer covers have an inner cover layer and an outer cover layer,and multi-layer covers additionally have at least one intermediate coverlayer disposed between the inner cover layer and the outer cover layer.Inner cover layers of the present invention preferably have a thicknesswithin a range having a lower limit of 0.010 or 0.015 or 0.020 or 0.025or 0.030 inches and an upper limit of 0.035 or 0.045 or 0.050 or 0.080or 0.120 or 0.150 or 0.200 inches. Outer cover layers of the presentinvention preferably have a thickness within a range having a lowerlimit of 0.010 or 0.015 or 0.020 or 0.025 inches and an upper limit of0.035 or 0.040 or 0.050 or 0.055 or 0.150 or 0.200 inches. Intermediatecover layer(s) of the present invention preferably have a thicknesswithin a range having a lower limit of 0.010 or 0.020 or 0.025 inchesand an upper limit of 0.050 or 0. 150 or 0.200 inches.

Suitable cover materials for golf balls of the present inventioninclude, but are not limited to, ionomer resins and blends thereof(e.g., Surlyn ionomer resins and DuPont® HPF 1000 and HPF 2000,commercially available from E. I. du Pont de Nemours and Company; Totek®ionomers, commercially available from ExxonMobil Chemical Company;Amplify® IO ionomers of ethylene acrylic acid copolymers, commerciallyavailable from The Dow Chemical Company; and Clarix® ionomer resins,commercially available from A. Schulman Inc.); polyurethanes, polyureas,and copolymers and blends of polyurethane and polyurea; polyethylene,including, for example, low density polyethylene, linear low densitypolyethylene, and high density polyethylene; polypropylene;rubber-toughened olefin polymers; acid copolymers, e.g., (meth)acrylicacid, which do not become part of an ionomeric copolymer; plastomers;flexomers; styrene/butadiene/styrene block copolymers;styrene/ethylene-butylene/styrene block copolymers; dynamicallyvulcanized elastomers; ethylene vinyl acetates; ethylene methylacrylates; polyvinyl chloride resins; polyamides, amide-esterelastomers, and graft copolymers of ionomer and polyamide, including,for example, Pebax® thermoplastic polyether block amides, commerciallyavailable from Arkema Inc; crosslinked trans-polyisoprene and blendsthereof; polyester-based thermoplastic elastomers, such as Hytrel®,commercially available from E. I. du Pont de Nemours and Company;polyurethane-based thermoplastic elastomers, such as Elastollan®,commercially available from BASF; synthetic and natural vulcanizedrubbers; and combinations thereof. Suitable cover materials andconstructions also include, but are not limited to, those disclosed inU.S. Pat. Nos. 6,117,025, 6,767,940, and 6,960,630, the entiredisclosures of which are hereby incorporated herein by reference.

Composition comprising an ionomer or a blend of two or more ionomers areparticularly suitable for forming inner cover layers. Preferredionomeric compositions include:

-   -   (a) a composition comprising a “high acid ionomer” (i.e., having        an acid content of greater than 16 wt %), such as Surlyn 8150®;    -   (b) a composition comprising a high acid ionomer and a maleic        anhydride-grafted non-ionomeric polymer (e.g., Fusabond® maleic        anhydride-grafted metallocene-catalyzed ethylene-butene        copolymers). A particularly preferred blend of high acid ionomer        and maleic anhydride-grafted polymer is a blend of 79-85 wt %        Surlyn 8150® and 15-21 wt % Fusabond . Blends of high acid        ionomers with maleic anhydride-grafted polymers are further        disclosed, for example, in U.S. Pat. Nos. 6,992,135 and        6,677,401, the entire disclosures of which are hereby        incorporated herein by reference;    -   (c) a composition comprising a 50/45/5 blend of Surlyn®        8940/Surlyn® 9650/Nucrel® 960, preferably having a material        hardness of from 80 to 85 Shore C;    -   (d) a composition comprising a 50/25/25 blend of Surlyn®        8940/Surlyn® 9650/Surlyn® 9910, preferably having a material        hardness of about 90 Shore C;    -   (e) a composition comprising a 50/50 blend of Surlyn®        8940/Surlyn® 9650, preferably having a material hardness of        about 86 Shore C;    -   (f) a composition comprising a blend of Surlyn® 7940/Surlyn®        8940, optionally including a melt flow modifier;    -   (g) a composition comprising a blend of a first high acid        ionomer and a second high acid ionomer, wherein the first high        acid ionomer is neutralized with a different cation than the        second high acid ionomer (e.g., 50/50 blend of Surlyn® 8150 and        Surlyn 9150), optionally including one or more melt flow        modifiers such as an ionomer, ethylene-acid copolymer or ester        terpolymer; and    -   (h) a composition comprising a blend of a first high acid        ionomer and a second high acid ionomer, wherein the first high        acid ionomer is neutralized with a different cation than the        second high acid ionomer, and from 0 to 10 wt % of an        ethylene/acid/ester ionomer wherein the ethylene/acid/ester        ionomer is neutralized with the same cation as either the first        high acid ionomer or the second high acid ionomer or a different        cation than the first and second high acid ionomers (e.g., a        blend of 40-50 wt % Surlyn® 8140, 40-50 wt % Surlyn® 9120, and        0-10 wt % Surlyn® 6320).

Surlyn 8150®, Surlyn® 8940, and Surlyn® 8140 are different grades ofE/MAA copolymer in which the acid groups have been partially neutralizedwith sodium ions. Surlyn® 9650, Surlyn® 9910, Surlyn® 9150, and Surlyn®9120 are different grades of E/MAA copolymer in which the acid groupshave been partially neutralized with zinc ions. Surlyn® 7940 is an E/MAAcopolymer in which the acid groups have been partially neutralized withlithium ions. Surlyn® 6320 is a very low modulus magnesium ionomer witha medium acid content. Nucrel® 960 is an E/MAA copolymer resin nominallymade with 15 wt % methacrylic acid. Surlyn® ionomers, Fusabond®copolymers, and Nucrel® copolymers are commercially available from E. I.du Pont de Nemours and Company.

Non-limiting examples of particularly preferred ionomeric cover layerformulations are shown in Table 1 below.

TABLE 1 Cover Layer Surlyn ® 8150, Fusabond ®, Shore C Hardness Materialwt % wt % at 10 Days 1 89 11 91.2 2 84 16 89.8 3 84 16 90.4 4 84 16 89.65 81 19 88.9 6 80 20 89.1 7 78 22 88.1 8 76 24 87.6 9 76 24 87.2 10 7327 86.6 11 71 29 86.7 12 67 33 84.0

Ionomeric cover compositions can be blended with non-ionic thermoplasticresins, particularly to manipulate product properties. Examples ofsuitable non-ionic thermoplastic resins include, but are not limited to,polyurethane, poly-ether-ester, poly-amide-ether, polyether-urea,thermoplastic polyether block amides (e.g., Pebax® block copolymers,commercially available from Arkema Inc.), styrene-butadiene-styreneblock copolymers, styrene(ethylene-butylene)-styrene block copolymers,polyamides, polyesters, polyolefins (e.g., polyethylene, polypropylene,ethylene-propylene copolymers, polyethylene-(meth)acrylate,plyethylene-(meth)acrylic acid, functionalized polymers with maleicanhydride grafting, Fusabond® functionalized olefins commerciallyavailable from E. I. du Pont de Nemours and Company, functionalizedpolymers with epoxidation, elastomers (e.g., ethylene propylene dienemonomer rubber, metallocene-catalyzed polyolefin) and ground powders ofthermoset elastomers.

Suitable ionomeric cover materials are further disclosed, for example,in U.S. Pat. Nos. 6,653,382, 6,756,436, 6,894,098, 6,919,393, and6,953,820, the entire disclosures of which are hereby incorporated byreference.

Polyurethanes, polyureas, and blends and hybrids ofpolyurethane/polyurea are particularly suitable for forming outer coverlayers. When used as cover layer materials, polyurethanes and polyureascan be thermoset or thermoplastic. Thermoset materials can be formedinto golf ball layers by conventional casting or reaction injectionmolding techniques. Thermoplastic materials can be formed into golf balllayers by conventional compression or injection molding techniques. Inembodiments of the present invention wherein a golf ball having a singlelayer cover is provided, the cover layer material is preferably selectedfrom polyurethane and polyurea. In embodiments of the present inventionwherein a golf ball having a dual cover is provided, the inner coverlayer is preferably a high modulus thermoplastic, and the outer coverlayer is preferably selected from polyurethane and polyurea.

Suitable polyurethane cover materials are further disclosed in U.S. Pat.Nos. 5,334,673, 6,506,851, 6,756,436, and 7,105,623, the entiredisclosures of which are hereby incorporated herein by reference.Suitable polyurea cover materials are further disclosed in U.S. Pat.Nos. 5,484,870 and 6,835,794, the entire disclosures of which are herebyincorporated herein by reference. Suitable polyurethane-urea covermaterials include polyurethane/polyurea blends and copolymers comprisingurethane and urea segments, as disclosed in U.S. Patent ApplicationPublication No. 2007/0117923, the entire disclosure of which is herebyincorporated herein by reference.

Golf ball cover compositions may include a flow modifier, such as, butnot limited to, Nucrel® acid copolymer resins, and particularly Nucrel®960. Nucrel® acid copolymer resins are commercially available from E. I.du Pont de Nemours and Company.

Cover compositions may also include one or more filler(s), such as thefillers given above for rubber compositions of the present invention(e.g., titanium dioxide, barium sulfate, etc.), and/or additive(s), suchas coloring agents, fluorescent agents, whitening agents, antioxidants,dispersants, UV absorbers, light stabilizers, plasticizers, surfactants,compatibility agents, foaming agents, reinforcing agents, releaseagents, and the like.

Additional suitable cover materials are disclosed, for example, in U.S.Patent Application Publication No. 2005/0164810, U.S. Pat. No.5,919,100, and PCT Publications WO00/23519 and WO00/29129, the entiredisclosures of which are hereby incorporated herein by reference.

In a particular embodiment, the cover is a single layer, preferablyformed from an ionomeric composition. The single layer cover preferablyhas an outer surface hardness of 65 Shore D or less, or 60 Shore D orless, or 45 Shore D or less, or 40 Shore D or less, or from 25 Shore Dto 40 Shore D, or from 30 Shore D to 40 Shore D, and a thickness withina range having a lower limit of 0.010 or 0.015 or 0.020 or 0.025 or0.030 or 0.050 inches and an upper limit of 0.065 or 0.080 or 0.090 or0.100 or 0.110 or 0.120 or 0.140 inches.

In another particular embodiment, the cover is a two-layer coverconsisting of an inner cover layer and an outer cover layer. The innercover layer is preferably formed from an ionomeric composition, andpreferably has an outer surface hardness of 60 Shore D or greater, or 65Shore D or greater, or an outer surface hardness within a range having alower limit of 30 or 40 or 55 or 60 or 65 Shore D and an upper limit of66 or 68 or 70 or 75 Shore D. The inner cover layer compositionpreferably has a material hardness of 95 Shore C or less, or less than95 Shore C, or 92 Shore C or less, or 90 Shore C or less, or 85 Shore Cor less, or has a material hardness within a range having a lower limitof 70 or 75 or 80 or 82 or 84 Shore C and an upper limit of 85 or 86 or90 or 92 or 95 Shore C. The inner cover layer preferably has a thicknesswithin a range having a lower limit of 0.010 or 0.015 or 0.020 or 0.025or 0.030 inches and an upper limit of 0.035 or 0.040 or 0.045 or 0.050or 0.055 or 0.075 or 0.080 or 0.100 or 0.110 or 0.120 inches. The outercover layer is preferably formed from a castable or reaction injectionmoldable polyurethane, polyurea, or copolymer or blend of polyurethaneand polyurea. Such cover material is preferably thermosetting, but maybe thermoplastic. The outer cover layer preferably has an outer surfacehardness of 60 Shore D or less, or an outer surface hardness of lessthan 60 Shore D, or an outer surface hardness within a range having alower limit of 20 or 30 or 35 or 40 Shore D and an upper limit of 52 or58 or 60 or 65 or 70 or 72 or 75 Shore D. The outer cover layercomposition preferably has a material hardness of 85 Shore C or less, or50 Shore D or less, or 45 Shore D or less, or 40 Shore D or less, orfrom 25 Shore D to 40 Shore D, or from 30 Shore D to 40 Shore D. Theouter cover layer preferably has a thickness within a range having alower limit of 0.010 or 0.015 or 0.020 or 0.025 or 0.030 inches and anupper limit of 0.035 or 0.040 or 0.045 or 0.050 or 0.055 or 0.075 or0.080 or 0.115 inches. The two-layer cover preferably has an overallthickness within a range having a lower limit of 0.020 or 0.025 or 0.030or 0.055 or 0.060 inches and an upper limit of 0.065 or 0.075 or 0.080or 0.090 or 0.100 or 0.110 or 0.120 or 0.140 inches.

Golf balls of the present invention optionally include one or moreintermediate layer(s) disposed between the core and the cover. Whenpresent, the overall thickness of the intermediate layer(s) is generallywithin a range having a lower limit of 0.010 or 0.050 or 0.100 inchesand an upper limit of 0.300 or 0.350 or 0.400 inches. Suitableintermediate layer materials include, but are not limited to, naturalrubbers, balata, gutta-percha, cis-polybutadienes, trans-polybutadienes,synthetic polyisoprene rubbers, polyoctenamers, styrene-propylene-dienerubbers, metallocene rubbers, styrene-butadiene rubbers,ethylene-propylene rubbers, chloroprene rubbers, acrylonitrile rubbers,acrylonitrile-butadiene rubbers, styrene-ethylene block copolymers,maleic anhydride- or succinate-modified metallocene catalyzed ethylenecopolymers, polypropylene resins, ionomer resins, polyamides,polyesters, polyurethanes, polyureas, chlorinated polyethylenes,polysulfide rubbers, fluorocarbons, and combinations thereof.

A moisture vapor barrier layer is optionally employed between the coreand the cover. Moisture vapor barrier layers are further disclosed, forexample, in U.S. Pat. Nos. 6,632,147, 6,932,720, 7,004,854, and7,182,702, the entire disclosures of which are hereby incorporatedherein by reference.

The present invention is not limited by any particular process forforming the golf ball layer(s). It should be understood that thelayer(s) can be formed by any suitable technique, including injectionmolding, compression molding, casting, and reaction injection molding.

When injection molding is used, the composition is typically in apelletized or granulated form that can be easily fed into the throat ofan injection molding machine wherein it is melted and conveyed via ascrew in a heated barrel at temperatures of from 150° F. to 600° F.,preferably from 200° F. to 500° F. The molten composition is ultimatelyinjected into a closed mold cavity, which may be cooled, at ambient orat an elevated temperature, but typically the mold is cooled to atemperature of from 50° F. to 70° F. After residing in the closed moldfor a time of from 1 second to 300 seconds, preferably from 20 secondsto 120 seconds, the core and/or core plus one or more additional core orcover layers is removed from the mold and either allowed to cool atambient or reduced temperatures or is placed in a cooling fluid such aswater, ice water, dry ice in a solvent, or the like.

When compression molding is used to form a center, the composition isfirst formed into a preform or slug of material, typically in acylindrical or roughly spherical shape at a weight slightly greater thanthe desired weight of the molded core. Prior to this step, thecomposition may be first extruded or otherwise melted and forced througha die after which it is cut into a cylindrical preform. It is thatpreform that is then placed into a compression mold cavity andcompressed at a mold temperature of from 150° F. to 400° F., preferablyfrom 250° F. to 350° F., and more preferably from 260° F. to 295° F.When compression molding a core or cover layer of an HNP composition, ahalf-shell is first formed via injection molding and then a corecomprising one or more layers is enclosed within two half shells andthen compression molded in a similar manner to the process previouslydescribed.

Reaction injection molding processes are further disclosed, for example,in U.S. Pat. Nos. 6,083,119, 7,338,391, 7,282,169, 7,281,997 and U.S.Patent Application Publication No. 2006/0247073, the entire disclosuresof which are hereby incorporated herein by reference.

Golf ball cores of the present invention typically have an overall corecompression of less than 100, or a compression of 87 or less, or anoverall core compression within a range having a lower limit of 20 or 50or 60 or 65 or 70 or 75 and an upper limit of 80 or 85 or 90 or 95 or100 or 110 or 120, or an overall core compression of about 80.Compression is an important factor in golf ball design. For example, thecompression of the core can affect the ball's spin rate off the driverand the feel. As disclosed in Jeff Dalton's Compression by Any OtherName, Science and Golf IV, Proceedings of the World Scientific Congressof Golf (Eric Thain ed., Routledge, 2002) (“J. Dalton”), severaldifferent methods can be used to measure compression, including Atticompression, Riehle compression, load/deflection measurements at avariety of fixed loads and offsets, and effective modulus. For purposesof the present invention, “compression” refers to Atti compression andis measured according to a known procedure, using an Atti compressiontest device, wherein a piston is used to compress a ball against aspring. The travel of the piston is fixed and the deflection of thespring is measured. The measurement of the deflection of the spring doesnot begin with its contact with the ball; rather, there is an offset ofapproximately the first 1.25 mm (0.05 inches) of the spring'sdeflection. Very low stiffness cores will not cause the spring todeflect by more than 1.25 mm and therefore have a zero compressionmeasurement. The Atti compression tester is designed to measure objectshaving a diameter of 42.7 mm (1.68 inches); thus, smaller objects, suchas golf ball cores, must be shimmed to a total height of 42.7 mm toobtain an accurate reading. Conversion from Atti compression to Riehle(cores), Riehle (balls), 100 kg deflection, 130-10 kg deflection oreffective modulus can be carried out according to the formulas given inJ. Dalton.

Golf ball cores of the present invention typically have a coefficient ofrestitution (“COR”) at 125 ft/s of 0.750 or greater, preferably 0.780 orgreater, and more preferably 0.790 or greater. COR, as used herein, isdetermined according to a known procedure wherein a golf ball or golfball subassembly (e.g., a golf ball core) is fired from an air cannon attwo given velocities and calculated at a velocity of 125 ft/s. Ballisticlight screens are located between the air cannon and the steel plate ata fixed distance to measure ball velocity. As the ball travels towardthe steel plate, it activates each light screen, and the time at eachlight screen is measured. This provides an incoming transit time periodinversely proportional to the ball's incoming velocity. The ball impactsthe steel plate and rebounds though the light screens, which againmeasure the time period required to transit between the light screens.This provides an outgoing transit time period inversely proportional tothe ball's outgoing velocity. COR is then calculated as the ratio of theoutgoing transit time period to the incoming transit time period,COR=V_(out)/V_(in)=T_(in)/T_(out).

Golf balls of the present invention will typically have dimple coverageof 60% or greater, preferably 65% or greater, and more preferably 75% orgreater.

The United States Golf Association specifications limit the minimum sizeof a competition golf ball to 1.680 inches. There is no specification asto the maximum diameter, and golf balls of any size can be used forrecreational play. Golf balls of the present invention can have anoverall diameter of any size. The preferred diameter of the present golfballs is from 1.680 inches to 1.800 inches. More preferably, the presentgolf balls have an overall diameter of from 1.680 inches to 1.760inches, and even more preferably from 1.680 inches to 1.740 inches.

Golf balls of the present invention preferably have a moment of inertia(“MOI”) of 70-95 g·cm², preferably 75-93 g·cm², and more preferably76-90 g·cm². For low MOI embodiments, the golf ball preferably has anMOI of 85 g·cm² or less, or 83 g·cm² or less. For high MOI embodiment,the golf ball preferably has an MOI of 86 g·cm or greater, or 87 g·cm orgreater. MOI is measured on a model MOI-005-104 Moment of InertiaInstrument manufactured by Inertia Dynamics of Collinsville, Conn. Theinstrument is connected to a PC for communication via a COMM port and isdriven by MOI Instrument Software version #1.2.

Thermoplastic layers herein may be treated in such a manner as to createa positive or negative hardness gradient. In golf ball layers of thepresent invention wherein a thermosetting rubber is used,gradient-producing processes and/or gradient-producing rubberformulation may be employed. Gradient-producing processes andformulations are disclosed more fully, for example, in U.S. patentapplication Ser. Nos. 12/048,665, filed on Mar. 14, 2008; 11/829,461,filed on Jul. 27, 2007; 11/772,903, filed Jul. 3, 2007; 11/832,163,filed Aug. 1, 2007; 11/832,197, filed on Aug. 1, 2007; the entiredisclosure of each of these references is hereby incorporated herein byreference.

In addition to the materials disclosed above, any of the core or coverlayers may comprise one or more of the following materials:thermoplastic elastomer, thermoset elastomer, synthetic rubber,thermoplastic vulcanizate, copolymeric ionomer, terpolymeric ionomer,polycarbonate, polyolefin, polyamide, copolymeric polyamide, polyesters,polyester-amides, polyether-amides, polyvinyl alcohols,acrylonitrile-butadiene-styrene copolymers, polyarylate, polyacrylate,polyphenylene ether, impact-modified polyphenylene ether, high impactpolystyrene, diallyl phthalate polymer, metallocene-catalyzed polymers,styrene-acrylonitrile (SAN), olefin-modified SAN,acrylonitrile-styrene-acrylonitrile, styrene-maleic anhydride (S/MA)polymer, styrenic copolymer, functionalized styrenic copolymer,functionalized styrenic terpolymer, styrenic terpolymer, cellulosepolymer, liquid crystal polymer (LCP), ethylene-propylene-diene rubber(EPDM), ethylene-vinyl acetate copolymer (EVA), ethylene propylenerubber (EPR), ethylene vinyl acetate, polyurea, and polysiloxane.Suitable polyamides for use as an additional material in compositionsdisclosed herein also include resins obtained by: (1) polycondensationof (a) a dicarboxylic acid, such as oxalic acid, adipic acid, sebacicacid, terephthalic acid, isophthalic acid or 1,4-cyclohexanedicarboxylicacid, with (b) a diamine, such as ethylenediamine,tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, ordecamethylenediamine, 1,4-cyclohexyldiamine or m-xylylenediamine; (2) aring-opening polymerization of cyclic lactam, such as ε-caprolactam orω-laurolactam; (3) polycondensation of an aminocarboxylic acid, such as6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid or12-aminododecanoic acid; or (4) copolymerzation of a cyclic lactam witha dicarboxylic acid and a diamine. Specific examples of suitablepolyamides include Nylon 6, Nylon 66, Nylon 610, Nylon 11, Nylon 12,copolymerized Nylon, Nylon MXD6, and Nylon 46.

Other materials suitable for use as an additional material in golf ballcompositions disclosed herein include Skypel polyester elastomers,commercially available from SK Chemicals of South Korea; Septon® diblockand triblock copolymers, commercially available from Kuraray Corporationof Kurashiki, Japan; and Kraton® diblock and triblock copolymers,commercially available from Kraton Polymers LLC of Houston, Tex.

Ionomers are also well suited for blending with compositions disclosedherein. Suitable ionomeric polymers include α-olefin/unsaturatedcarboxylic acid copolymer- or terpolymer-type ionomeric resins.Copolymeric ionomers are obtained by neutralizing at least a portion ofthe carboxylic groups in a copolymer of an α-olefin and anα,β-unsaturated carboxylic acid having from 3 to 8 carbon atoms, with ametal ion. Terpolymeric ionomers are obtained by neutralizing at least aportion of the carboxylic groups in a terpolymer of an α-olefin, anα,β-unsaturated carboxylic acid having from 3 to 8 carbon atoms, and anα,β-unsaturated carboxylate having from 2 to 22 carbon atoms, with ametal ion. Examples of suitable α-olefins for copolymeric andterpolymeric ionomers include ethylene, propylene, 1-butene, and1-hexene. Examples of suitable unsaturated carboxylic acids forcopolymeric and terpolymeric ionomers include acrylic, methacrylic,ethacrylic, α-chloroacrylic, crotonic, maleic, fumaric, and itaconicacid. Copolymeric and terpolymeric ionomers include ionomers havingvaried acid contents and degrees of acid neutralization, neutralized bymonovalent or bivalent cations as disclosed herein. Examples ofcommercially available ionomers suitable for blending with compositionsdisclosed herein include Surlyn® ionomer resins, commercially availablefrom E. I. du Pont de Nemours and Company, and Iotek® ionomers,commercially available from ExxonMobil Chemical Company.

Silicone materials are also well suited for blending with compositionsdisclosed herein. Suitable silicone materials include monomers,oligomers, prepolymers, and polymers, with or without adding reinforcingfiller. One type of silicone material that is suitable can incorporateat least 1 alkenyl group having at least 2 carbon atoms in theirmolecules. Examples of these alkenyl groups include, but are not limitedto, vinyl, allyl, butenyl, pentenyl, hexenyl, and decenyl. The alkenylfunctionality can be located at any location of the silicone structure,including one or both terminals of the structure. The remaining (i.e.,non-alkenyl) silicon-bonded organic groups in this component areindependently selected from hydrocarbon or halogenated hydrocarbongroups that contain no aliphatic unsaturation. Non-limiting examples ofthese include: alkyl groups, such as methyl, ethyl, propyl, butyl,pentyl, and hexyl; cycloalkyl groups, such as cyclohexyl andcycloheptyl; aryl groups, such as phenyl, tolyl, and xylyl; aralkylgroups, such as benzyl and phenethyl; and halogenated alkyl groups, suchas 3,3,3-trifluoropropyl and chloromethyl. Another type of suitablesilicone material is one having hydrocarbon groups that lack aliphaticunsaturation. Specific examples include: trimethylsiloxy-endblockeddimethylsiloxane-methylhexenylsiloxane copolymers;dimethylhexenylsiloxy-endblocked dimethylsiloxane-methylhexenylsiloxanecopolymers; trimethylsiloxy-endblockeddimethylsiloxane-methylvinylsiloxane copolymers;trimethylsiloxyl-endblockedmethylphenylsiloxane-dimethylsiloxane-methylvinysiloxane copolymers;dimethylvinylsiloxy-endblocked dimethylpolysiloxanes;dimethylvinylsiloxy-endblocked dimethylsiloxane-methylvinylsiloxanecopolymers; dimethylvinylsiloxy-endblocked methylphenylpolysiloxanes;dimethylvinylsiloxy-endblockedmethylphenylsiloxane-dimethylsiloxane-methylvinylsiloxane copolymers;and the copolymers listed above wherein at least one group isdimethylhydroxysiloxy. Examples of commercially available siliconessuitable for blending with compositions disclosed herein includeSilastic® silicone rubber, commercially available from Dow ComingCorporation of Midland, Mich.; Blensil® silicone rubber, commerciallyavailable from General Electric Company of Waterford, N.Y.; andElastosil® silicones, commercially available from Wacker Chemie AG ofGermany.

Other types of copolymers can also be added to the golf ballcompositions disclosed herein. For example, suitable copolymerscomprising epoxy monomers include styrene-butadiene-styrene blockcopolymers in which the polybutadiene block contains an epoxy group, andstyrene-isoprene-styrene block copolymers in which the polyisopreneblock contains epoxy. Examples of commercially available epoxyfunctionalized copolymers include ESBS A1005, ESBS A1010, ESBS A1020,ESBS AT018, and ESBS AT019 epoxidized styrene-butadiene-styrene blockcopolymers, commercially available from Daicel Chemical Industries, Ltd.of Japan.

Ionomeric compositions used to form golf ball layers of the presentinvention can be blended with non-ionic thermoplastic resins,particularly to manipulate product properties. Examples of suitablenon-ionic thermoplastic resins include, but are not limited to,polyurethane, poly-ether-ester, poly-amide-ether, polyether-urea, Pebax®thermoplastic polyether block amides commercially available from ArkemaInc., styrene-butadiene-styrene block copolymers,styrene(ethylene-butylene)-styrene block copolymers, polyamides,polyesters, polyolefins (e.g., polyethylene, polypropylene,ethylene-propylene copolymers, ethylene-(meth)acrylate,ethylene-(meth)acrylic acid, functionalized polymers with maleicanhydride grafting, epoxidation, etc., elastomers (e.g., EPDM,metallocene-catalyzed polyethylene) and ground powders of the thermosetelastomers.

For purposes of the present disclosure, material hardness is measuredaccording to ASTM D2240 and generally involves measuring the hardness ofa flat “slab” or “button” formed of the material. It should beunderstood that there is a fundamental difference between “materialhardness” and “hardness as measured directly on a golf ball.” Hardnessas measured directly on a golf ball (or other spherical surface)typically results in a different hardness value than material hardness.This difference in hardness values is due to several factors including,but not limited to, ball construction (i.e., core type, number of coreand/or cover layers, etc.), ball (or sphere) diameter, and the materialcomposition of adjacent layers. It should also be understood that thetwo measurement techniques are not linearly related and, therefore, onehardness value cannot easily be correlated to the other.

Golf ball cores of the present invention may have a zero or negative orpositive hardness gradient. For purposes of the present disclosure, ahardness gradient of a golf ball layer is defined by hardnessmeasurements made at the outer surface of the layer and the innersurface of the layer. The inner core layer's center hardness and theouter core layer's outer surface hardness are readily determinedaccording to the procedures given herein for measuring the centerhardness of a core and the outer surface hardness of a golf ball layer,respectively. The outer surface of the inner core layer is readilydetermined according to the procedures given herein for measuring theouter surface hardness of a golf ball layer, if the measurement is madeprior to surrounding the layer with the outer core layer. However, oncethe inner core layer is surrounded by the outer core layer, the hardnessof the inner core layer's outer surface can be difficult to determine.Thus, for purposes of the present invention:

-   -   the center hardness of the inner core layer is measured        according to the procedure below for measuring the center        hardness of a core;    -   the hardness of the outer surface of the inner core layer is        measured:        -   prior to surrounding the inner core layer with the outer            core layer, according to the procedure below for measuring            the outer surface hardness of a golf ball layer;        -   after surrounding the inner core layer with the outer core            layer, according to the procedure below for measuring a            point located 1 mm from an interface;    -   the hardness of the outer surface of the outer core layer is        measured according to the procedure below for measuring the        outer surface hardness of a golf ball layer.

The center hardness of a core is obtained according to the followingprocedure. The core is gently pressed into a hemispherical holder havingan internal diameter approximately slightly smaller than the diameter ofthe core, such that the core is held in place in the hemisphericalportion of the holder while concurrently leaving the geometric centralplane of the core exposed. The core is secured in the holder byfriction, such that it will not move during the cutting and grindingsteps, but the friction is not so excessive that distortion of thenatural shape of the core would result. The core is secured such thatthe parting line of the core is roughly parallel to the top of theholder. The diameter of the core is measured 90 degrees to thisorientation prior to securing. A measurement is also made from thebottom of the holder to the top of the core to provide a reference pointfor future calculations. A rough cut is made slightly above the exposedgeometric center of the core using a band saw or other appropriatecutting tool, making sure that the core does not move in the holderduring this step. The remainder of the core, still in the holder, issecured to the base plate of a surface grinding machine. The exposed‘rough’ surface is ground to a smooth, flat surface, revealing thegeometric center of the core, which can be verified by measuring theheight from the bottom of the holder to the exposed surface of the core,making sure that exactly half of the original height of the core, asmeasured above, has been removed to within ±0.004 inches. Leaving thecore in the holder, the center of the core is found with a center squareand carefully marked and the hardness is measured at the center markaccording to ASTM D-2240. Additional hardness measurements at anydistance from the center of the core can then be made by drawing a lineradially outward from the center mark, and measuring the hardness at anygiven distance along the line, typically in 2 mm increments from thecenter. The hardness at a particular distance from the center should bemeasured along at least two, preferably four, radial arms located 180°apart, or 90° apart, respectively, and then averaged. All hardnessmeasurements performed on a plane passing through the geometric centerare performed while the core is still in the holder and without havingdisturbed its orientation, such that the test surface is constantlyparallel to the bottom of the holder, and thus also parallel to theproperly aligned foot of the durometer.

The outer surface hardness of a golf ball layer is measured on theactual outer surface of the layer and is obtained from the average of anumber of measurements taken from opposing hemispheres, taking care toavoid making measurements on the parting line of the core or on surfacedefects, such as holes or protrusions. Hardness measurements are madepursuant to ASTM D-2240 “Indentation Hardness of Rubber and Plastic byMeans of a Durometer.” Because of the curved surface, care must be takento insure that the golf ball or golf ball subassembly is centered underthe durometer indentor before a surface hardness reading is obtained. Acalibrated, digital durometer, capable of reading to 0.1 hardness unitsis used for all hardness measurements and is set to take hardnessreadings at 1 second after the maximum reading is obtained. The digitaldurometer must be attached to, and its foot made parallel to, the baseof an automatic stand. The weight on the durometer and attack rateconform to ASTM D-2240.

The hardness of a golf ball layer at a point located 1 mm from aninterface is obtained according to the following procedure. First, thegeometric center of the core is revealed by preparing the core accordingto the above procedure for measuring the center hardness of a core.Leaving the core in the holder, a point located 1 mm radially inward oroutward from the interface of two layers is determined and marked, andthe hardness thereof is measured according to ASTM D-2240. Whenmeasuring the outer surface of a layer, the mark is made at a pointlocated 1 mm radially inward from the interface at the outermost part ofthe layer. When measuring the inner surface of a layer, the mark is madeat a point located 1 mm radially outward from the interface at theinnermost part of the layer.

Hardness points should only be measured once at any particular geometriclocation.

For purposes of the present invention, “negative” and “positive” referto the result of subtracting the hardness value at the innermost surfaceof the golf ball component from the hardness value at the outermostsurface of the component. For example, if the outer surface of a solidcore has a lower hardness value than the center (i.e., the surface issofter than the center), the hardness gradient will be deemed a“negative” gradient.

Hardness gradients are disclosed more fully, for example, in U.S. patentapplication Ser. No. 11/832,163, filed on Aug. 1, 2007; U.S. patentapplication Ser. No. 11/939,632, filed on Nov. 14, 2007; U.S. patentapplication Ser. No. 11/939,634, filed on Nov. 14, 2007; U.S. patentapplication Ser. No. 11/939,635, filed on Nov. 14, 2007; and U.S. patentapplication Ser. No. 11/939,637, filed on Nov. 14, 2007; the entiredisclosure of each of these references is hereby incorporated herein byreference.

EXAMPLES

It should be understood that the examples below are for illustrativepurposes only. In no manner is the present invention limited to thespecific disclosures herein.

Additional Examples of Suitable HNPs

The HNPs of Table 2 below have been found to be particularly useful asthe low modulus HNP and/or the high modulus HNP of the presentinvention.

TABLE 2 Flexural Hardness**, Hardness**, cation Modulus*, Shore C ShoreD Example source psi (18 day) (annealed) 1 Ca/Mg 71,600 88 57 2 Ca/Li70,300 89 58 3 Ca 70,100 92 60 4 Ca/Zn 60,400 88 58 5 Mg 38,300 84 52 6Mg 27,600 84 52 7 Mg 16,300 78 45 8 Mg 10,600 70 40 9 Mg 10,400 69 39*Flexural modulus was measured according to ASTM D790-03 Procedure B.**Hardness was measured according to ASTM D2240.

In embodiments of the present invention directed to a golf ball havingan inner core layer formed from a low modulus HNP composition, Examples6-9 are particularly suitable for use as the low modulus HNPcomposition.

In embodiments of the present invention directed to a golf ball havingan outer core layer formed from a low modulus HNP composition, Examples5-9 are particularly suitable for use as the low modulus HNPcomposition.

In embodiments of the present invention directed to a golf ball havingan inner core layer formed from a high modulus HNP composition, Examples1-6 are particularly suitable for use as the high modulus HNPcomposition.

In embodiments of the present invention directed to a golf ball havingan outer core layer formed from a high modulus HNP composition, Examples1-4 are particularly suitable for use as the high modulus HNPcomposition.

Additional Examples of Suitable Ionomeric Cover Layer Compositions

Twelve ionomeric inner cover layer compositions according to the presentinvention were prepared by melt blending Surlyn® 8150 and Fusabond® 572Din a twin screw extruder, at a temperature of at least 450° F. (230°C.). The relative amounts of each component used are indicated in Table2 below.

Flex bars of each blend composition were formed and evaluated forhardness according to ASTM D2240 following 10 days of aging at 50%relative humidity and 23° C. The results are reported in Table 3 below.

TABLE 3 Surlyn ® 8150, Fusabond ® Shore C Hardness Example wt % 572D, wt% at 10 Days 1 89 11 91.2 2 84 16 89.8 3 84 16 90.4 4 84 16 89.6 5 81 1988.9 6 80 20 89.1 7 78 22 88.1 8 76 24 87.6 9 76 24 87.2 10 73 27 86.611 71 29 86.7 12 67 33 84.0

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

1. A golf ball consisting of a core and a cover, wherein the core has anoverall diameter of from 1.400 inches to 1.660 inches and consists of:an inner core layer having a diameter of from 0.125 inches to 0.750inches, an outer surface hardness of 70 Shore C or greater, and formedfrom a high modulus HNP composition, the high modulus HNP compositioncomprising a highly neutralized ethylene/(meth)acrylic acid copolymerhaving a modulus of from 25,000 psi to 150,000 psi; and an outer corelayer having an outer surface hardness less than the outer surfacehardness of the inner core layer and formed from a low modulus HNPcomposition, the low modulus HNP composition comprising a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymerhaving a modulus of from 1,000 psi to 50,000 psi; wherein the modulus ofthe highly neutralized copolymer of the low modulus HNP composition isat least 10% less than the modulus of the highly neutralized copolymerof the high modulus HNP composition.
 2. The golf ball of claim 1,wherein the outer core layer has a specific gravity greater than orequal to the inner core layer specific gravity.
 3. The golf ball ofclaim 1, wherein the core has an overall diameter of from 1.510 inchesto 1.600 inches.
 4. The golf ball of claim 1, wherein the inner corelayer has a diameter of from 0.250 inches to 0.375 inches.
 5. The golfball of claim 1, wherein the inner core layer has an outer surfacehardness of 85 Shore C or greater.
 6. The golf ball of claim 1, whereinthe outer core layer has an outer surface hardness of 80 Shore C orless.
 7. The golf ball of claim 1, wherein the cover consists of asingle layer having an outer surface hardness of 60 Shore D or less anda thickness of from 0.015 inches to 0.100 inches.
 8. The golf ball ofclaim 1, wherein the cover consists of: an inner cover layer having anouter surface hardness of 65 Shore D or greater and a thickness of from0.020 inches to 0.080 inches; and an outer cover layer having an outersurface hardness of 60 Shore D or less and a thickness of from 0.015inches to 0.055 inches.
 9. The golf ball of claim 1, wherein the coverconsists of: an inner cover layer formed from a partially or fullyneutralized polymer composition and having an outer surface hardness of65 Shore D or greater and a thickness of from 0.015 inches to 0.035inches; and an outer cover layer formed from a polyurethane or polyureacomposition and having a material hardness of 50 Shore D or less and athickness of from 0.015 inches to 0.035 inches.
 10. A golf ballconsisting of: a core having an overall diameter of from 1.400 inches to1.620 inches and consisting of: an inner core layer having a diameter offrom 0.250 inches to 0.500 inches, an outer surface hardness of 81 ShoreC or greater, and formed from a high modulus HNP composition, the highmodulus HNP composition comprising a highly neutralizedethylene/(meth)acrylic acid copolymer having a modulus of from 25,000psi to 150,000 psi; and an outer core layer having an outer surfacehardness of 90 Shore C or less and formed from a low modulus HNPcomposition, the low modulus HNP composition comprising a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymerhaving a modulus of from 1,000 psi to 50,000 psi; and a cover consistingof: an inner cover layer having an outer surface hardness of 65 Shore Dor greater and a thickness of from 0.020 inches to 0.080 inches; and anouter cover layer having a surface hardness of 60 Shore D or less and athickness of from 0.015 inches to 0.055 inches; wherein the modulus ofthe highly neutralized copolymer of the low modulus HNP composition isat least 10% less than the modulus of the highly neutralized copolymerof the high modulus HNP composition.
 11. The golf ball of claim 10,wherein the outer core layer has a specific gravity greater than orequal to the inner core layer specific gravity.
 12. The golf ball ofclaim 10, wherein the core has an overall diameter of from 1.510 inchesto 1.600 inches.
 13. The golf ball of claim 10, wherein the inner corelayer has a diameter of from 0.250 inches to 0.375 inches.
 14. The golfball of claim 10, wherein the inner core layer has an outer surfacehardness of 85 Shore C or greater.
 15. The golf ball of claim 14,wherein the outer core layer has an outer surface hardness of 80 Shore Cor less.
 16. The golf ball of claim 10, wherein the outer surfacehardness of the outer core layer is less than the outer surface hardnessof the inner core layer.